Relay for two-wire notching systems.



E. R. OARIGHOPF. RELAY FOR TWO-WIRE NOTGHING SYSTEMS.

APPLIOATIOKIILED AUG. 9, 1911.

1,077,972. Patented Nov. 11, 1913.

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. b 1 Witnesses: 1 Inventor 1 {M 444 Eu eneR.C r'ichoff,

His fittorneg.

B. R. GARICHOFF.

I RELAY FOR TWO-WIRE NOTOHING SYSTEMS.

APPLICATION FILED AUGSQ, 1911.

7 1 077 972; Patented Nov. 11, 1913.

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Fig.3.

Fig. 2.

o w o UNITED STATES PATENT OFFICE.

EUGENE R. CARICHOFF, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RELAY FOR TWO-WIRE NOTGHING SYSTEMS.

Specification of Letters Patent.

Patented Nov. 1. 1, 1913.

I Application filed August 9, 1911. Serial No. 643,086.

- tion in succession: such, for example, as are customarily used in controlling electric railway motors.

' The present invention has especial reference to the system of control disclosed in my Patent 982,082, January 17 1911. In this patent, and also in my pending application filed August 12, 1910, Serial No. 576,927, I have shown arelay in which there is a series coil gr coils whiclnhold the relay open until the current value decreases to a certain point. Insaid application the series coil is shown as provided with an adjustable core, in order to regulate its influence upon thecores of the relay coils. The present caserelates to improvements in the structure of said relay in order to obtain with more accuracy a varying current limit to suit varying conditions of service. This coil can be set to hold at ahigh current so that the car will mount grades, and yet this high current-will not occur on levels. The construction'is such that as the current in the series coilf increases, the time of descent of the relay-plunger increases, so that the intervals between the'operation of the contactors will increase correspondingly, and the motor will speed up more slowly. The plunger of the relay coil has a dashpot which would ordinarily permit it to descend in the same time after each deenergizing of the relay coil. In order to retard this descent in accordance with the current in the series coil, I cause the magnetic field of the series coil to afi'ect the plunger, and resist to a greater or less extent the downward pull of gravity tending to close therelay contacts. Adjustabilityis obtained by movable cores in the series coil which can be adjusted to give a greater or less air gap in. the magnetic circuit. There is also an adjustable stop in the upper end of the relay 51300] which varies referred to.

the vertical lay of the movable core or plunger of said relay. The spool has a fixed tubular core or bushing which cotiperates with the movable core to determine the point at which the plunger will hang sus.

pended. When the car is running on a level, the plunger will drop quicker than when the car is mounting a grade, because the load is less and the motor willmore quickly generate suiiicient counterelectromotive force to cut down the current and counteract the retarding effect of the series coil.

In the accompanying drawings, Figure 1 is a diagram of a two wire notcnin system of motor control; Fig. 2 is a front e evation, partly in section, of the relay; and Fig. 3 is an end elevation of the same.

There is nothing novel in the. system shown in Fi 1,'and it has been'fully disclosed and escribed in my patent above In brief, it may be said here that when the master controller 0 is moved to the position at, the relay'L will be energized, its circuit being traceable from the finger c to wire 1, solenoid L, interlock 2 on the core of the relay R, wires 34, interlock 5, on the movable core of the contactor 6, coil 7 of said contactor and wire 8 to ground at G. The bridging contact of the interlock 5 is loose on the stem of the contactor core, and is not lifted by the collar 9 thereon until after the interlock 10 on said stem has closed a holding circuit 11 established throughthe finger b of the con troller. The lifting of the contactor' stem also causes the interlock 12 to close a circuit from the wire 1 by way of the solenoid R, interlock 18 on the plunger of the relay L, wires 14, 15, 16, interlock 17 on the stem of the contactor 18, solenoid 19 of said contactor and wire 8 to ground. This circuit, however, has been opened at the interlock 13 when the relay L was energized and its plunger lifted, and the said circuit of the relay R will not be established until the plunger of relay L-descends. The closing of the contactor 6 sends current to the motor M through the resistors R, R R. The second cont-actor 18 will cut out the first resistor, but this cannot take place until the plunger of relay L descends and closes the interlock 13. Its descent is retarded both mechanically and electrically; the latter effect being produced by the series coil 20.

in the power circuit of the motor M from the rclay 'ilungers to drop, the rate of accelthe button a of the master controller C, and acting to give a variable time limit to the descent of the plunger.

Referring now to Figs. 2 and 3, the relay is seen to have a frame composed of two parallel bars 21 22 of iron or other magnetic material spaced apartby posts 23 of brass or other non-magnetic material. Between said bars is located the series coil 20 composed of a few turns of heavy conductor Wound on a tube'2 l of insulating material clamped between thebars. Cores 25 25 are tapped through said bars and project into the tube2 t, affording means for adjusting the length. of the air gap 26 between their ends. The relay coils 27 28 are wound on spools of insulating material which are clamped between the ends of the bars 21 22, one on each side of the series coil. Each spool has a tubular bushing, the lower portion 29 being of brass or other non-magnetic material and the upper portion. 30 being of steel or other magnetic material. The bushing 30 is extended upwardly through a hole in the bar 21 and is tapped to receive a brass screw plug 31 which serves as an adjustable stop to limit the upward movement of the movable core plunger 32 which has a sliding fit in the bushing of the spool, and extends down-through a hole in the lower bar 22. The vertical play of the plunger when the adjustingscrew is run up to the top of the, spool is preferably about three-quarters of an inch. The plunger carries a contact disk 33 fittin loosely on said plunger, and held yielding y on a shoulder 34 by a spring 35. 'This disk makes contact with the contacts 36 supported on brackets 37. On the lower end of the plunger is secured the moventire range of movement in-about eight-- tenths of a second when there is no current flowing in the coils. At 39 is shown the terminal for connecting the wire 1 of Fig. 1, and at 40 41 are the terminals for the wires 3 and 14:.

The principle of operation of the two wire notching system is, that so long as the operator keeps the master controller fully closed the contactors will close automatically in succession until all the resistors have been out out and the motor is connected directly to the line. Each contactor as it closes also closes a break in the circuit of the next contactor, and this circuit is'completed when the plunger of the relay in circuit with the eration of the motor can be controlled. The relay construction above described enables this control to be very accurately exerted.

Assume that when the master cont-roller C is moved to position a: the current permitted to flow through the resistors R, R R to the motor is 250 amperes. This current, passing through the series coil 20, will set up a magnetic flux in the cores 25 25, the bars 21 22, the bushin 30 and the lunger. 32, which will be sufli cient to just alance the weight of said plunger when it has been lifted, by the coil 27. Upon the deenergizing of the coil 27 the plunger will start to drop and will descend easily'until its top reaches the lower end of the bushing 30. Here the flux set up by the series coil will oppose the lengthening of its path by the separation of the plunger from the bushing, and therefore the plunger will be sustained in this position indefinitely by the flux generated by this current of say, 250 amperes. I So long, therefore, as the current flowing to the motor remains at this value the interlock 13 w11l not close, and no more resistors will be'cut out. But when the motor speeds up and its counterelectromotive force cuts down the current, the sustaining power of the series coil becomes weaker, and the plunger begins to descend. Its descent is opposed by thedash-pot 38, and its speed for the plunger to drop completely; at 200 am eres the descent will occur in 2.1 secon s; at l50 amperes in 1.7 seconds, and so on. The more rapidly the current is cut down the faster the plunger will drop. If,

therefore, the car starts on a level road,

where it can accelerate rapidly, the contactors will close quickly and cut out the I successive resistors in a short time. But when the car is on an up grade the rate at which the current will be cut down by the counterelectromotive force of the motor will be slower, and consequently the descent of the plungers will be slower, owing to the greater retarding effect of the seriescoil flux. This revents the resistors from being cut out whi e the current remains at a high value, cuts them out very slowly if the current drops only a little below that value, and more rapidly if the drop is greater.

The minimum current at'which the series coil will hold the plunger from dropping can be varied by screwing the cores 25 25 in or out to vary the length of the air gap 26 in the magnetic circuit of said coil; the holding current being higherwhen the length of the gap increases and vice versa.

The adjusting screw 31 permits of varying the stroke of the dashpot and thereby varywith the apparatus w ich I now consider by Letters Patent of the United States, is,

ing to some extent the time of descent of the plunger.

In accordance with the provisions of the patent statutes I have described the principle of operation of m invention, together to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the'inv'ention can be carried out by other means.

What I claim as new and desire to secure 1. A system of motor control comprising a relay having magnetic plunger-s controlling circuits, coils for lifting said plungers, dashpots for retarding their descent, a magnetic structure including said plungers, and a series coil with cores connected with said structure for setting up a flux in said structure.

A system of motor control comprising a relay having magnetic plungers control ling c1rcuits, coils for lifting said plungers, dash-pots for retarding their descent, a magnetic structure including said plunger-s and in which their descent increases an'air gap, and a series coil for setting up a flux in said structure.

A system of motor control comprising a relay having two bars of magnetic material, relay coils between said bars, bushings for the spools of said coils, composed in part of magnetic material, magnetic circuit controlling plungers working in said bushings, means for retarding the descent of said Copies of this patent may be obtained for five cents plunger-s, and a series coil between Sflh'l bars with cores connected with said bars.

4:. A relay comprising two bars of magnetic material, cores tapped into said bars, a series coil concentric with said cores, relay coils between said bars, bushings for said coils whose upper portions only are magnetic, and circuit controlling plungers of magnetic material entering the lower part of said relay coils.

5. A relay comprising two bars of magnetic material, cores tapped into said bars, a series coil concentric with said cores, relay coils between said bars, bushings for said coils whose upper portions only are magnetic, circuit controlling 'plungers of magnetic material enterin the-lower part of said relay coils, and a justable stops entering the upper part of said relay coils.

63A re ay comprising two bars of magnetic material, cores tapped into said bars,

a series coil concentric with said cores, relay coils between said bars, bushings for said coils whose upper portions only are magnetic, circuit controlling plungers of magnetic material entering the lower part of said relay coils, and dash-pots connected to said plungers for retarding the descent thereof.

In witness whereof, I have hereunto set my hand this 7th day of August, 1911.

EUGENE R. GARIOHOFF.

' Witnesses:

HELEN Onronn, BENJAMIN B. HULL.

each, by addressing the Commissioner of Patents,

Washington, D. C. 

